import sys
import pygame
from bullet import Bullet
from alien import Alien
from time import sleep

def check_events(ai_settings, screen, stats, sb, play_button, ship, aliens, bullets):
	""" 响应按键和鼠标事件 """
	for event in pygame.event.get():
		if event.type == pygame.QUIT:
			sys.exit()
		elif event.type == pygame.KEYDOWN:
			check_keydown_events(event, ai_settings, screen, ship, bullets)

		elif event.type == pygame.KEYUP:
			check_keyup_events(event, ship)
		elif event.type == pygame.MOUSEBUTTONDOWN:
			mouse_x, mouse_y = pygame.mouse.get_pos()
			check_play_button(ai_settings, screen, stats, sb, play_button, ship, aliens, bullets, mouse_x, mouse_y)

def check_keydown_events(event, ai_settings, screen, ship, bullets):
	""" 响应按键 """
	if event.key == pygame.K_RIGHT:
		# 按下时,并更改移动标志
		ship.moving_right = True
	elif event.key == pygame.K_LEFT:
		ship.moving_left = True
	elif event.key == pygame.K_UP:
		ship.moving_up = True
	elif event.key == pygame.K_DOWN:
		ship.moving_down = True
	elif event.key == pygame.K_SPACE:
		# 创建一个子弹，并将其加入到编组bullets中
		fire_bullet(ai_settings, screen, ship, bullets)
	elif event.key == pygame.K_q:
		# 按下q时关闭程序
		sys.exit()

def check_keyup_events(event, ship):
	""" 响应松开 """
	if event.key == pygame.K_RIGHT:
		# 松开按键时，更改移动标志
		ship.moving_right = False
	elif event.key == pygame.K_LEFT:
		ship.moving_left = False
	elif event.key == pygame.K_UP:
		ship.moving_up = False
	elif event.key == pygame.K_DOWN:
		ship.moving_down = False

def check_play_button(ai_settings, screen, stats, sb, play_button, ship, aliens, bullets, mouse_x, mouse_y):
	"""在玩家单击Play按钮时开始游戏"""
	button_clicked = play_button.rect.collidepoint(mouse_x, mouse_y)
	if button_clicked and not stats.game_active:
		# 重置游戏设置
		ai_settings.initialize_dynamic_settings()

		# 隐藏光标
		pygame.mouse.set_visible(False)

		# 重置游戏系统信息
		stats.reset_stats()
		stats.game_active = True

		# 重置计分牌图像
		sb.prep_score()
		sb.prep_high_score()
		sb.prep_level()
		sb.prep_ships()

		# 清空外星人列表和子弹列表
		aliens.empty()
		bullets.empty()

		# 创建群新的外星人,并让飞船居中
		create_fleet(ai_settings, screen, ship, aliens)
		ship.center_ship()

def update_screen(ai_settings, screen, stats, sb, ship, aliens, bullets, play_button):
	""" 更新屏幕上的图像，并切换到新屏幕 """
	# 每次循环时都会重新绘制屏幕
	screen.fill(ai_settings.bg_color)
	# 在飞船和外星人后面绘制所有子弹
	for bullet in bullets.sprites():
		bullet.draw_bullet()

	ship.blitme()
	aliens.draw(screen)
	# 显示得分
	sb.show_score()

	# 如果游戏处于非活动状态，就绘制play按钮
	if not stats.game_active:
		play_button.draw_button()

	# 让最近的绘制的在屏幕可见
	pygame.display.flip()

def update_bullets(ai_settings, screen, stats, sb, ship, aliens, bullets):
	"""更新子弹的位置，并删除已消失的子弹"""
	# 更新子弹的位置
	bullets.update()

	# 删除消失的子弹
	for bullet in bullets.copy():
		if bullet.rect.bottom <= 0:
			bullets.remove(bullet)
	# 打印消失的子弹数
	# print(len(bullets))
	check_bullet_alien_collisions(ai_settings, screen, stats, sb, ship, aliens, bullets)
	
def check_bullet_alien_collisions(ai_settings, screen,  stats, sb, ship, aliens, bullets):
	"""响应子弹和外星人的碰撞"""
	# 检查是否有子弹击中外星人
	# 如果是这样，就删除相应的子弹和外星人
	collisions = pygame.sprite.groupcollide(bullets, aliens, True, True)

	if collisions:
		for aliens in collisions.values():
			stats.score += ai_settings.alien_points * len(aliens)
			sb.prep_score()
		check_high_score(stats, sb)

	if len(aliens) == 0:
		# 如果整群外星人都被消灭了,就提高一个等级
		# 删除现有的子弹,加快游戏节奏,并新建一群外星人
		bullets.empty()
		ai_settings.increase_speed()

		# 提高等级
		stats.level += 1
		sb.prep_level()

		create_fleet(ai_settings, screen, ship, aliens)
	
def fire_bullet(ai_settings, screen, ship, bullets):
	"""如果还没有到达限制，就发射一颗子弹"""
	# 创建一个子弹，并将其加入到编组bullets中
	if len(bullets) < ai_settings.bullets_allowed:
		new_bullet = Bullet(ai_settings, screen, ship)
		bullets.add(new_bullet)

def create_fleet(ai_settings, screen, ship, aliens):
	"""创建外星人群"""
	# 创建一个外星人，并计算一行可容纳多少个外星人
	# 外星人间距为外星人的宽度
	alien = Alien(ai_settings, screen)
	number_alien_x = get_number_aliens_x(ai_settings, alien.rect.width)
	number_rows = get_number_rows(ai_settings, ship.rect.height, alien.rect.height)

	# 创建外星人群
	for row_number in range(number_rows):
		for alien_number in range(number_alien_x):
			create_alien(ai_settings, screen, aliens, alien_number, row_number)

def get_number_aliens_x(ai_settings, alien_width):
	"""计算每行可容纳多少个外星人"""
	available_space_x = ai_settings.screen_width - 2 * alien_width
	number_alien_x = int(available_space_x / (2 * alien_width))
	return number_alien_x

def create_alien(ai_settings, screen, aliens, alien_number, row_number):
	"""创建一个外星人并将其放在当前行"""
	alien = Alien(ai_settings, screen)
	alien_width = alien.rect.width
	alien.x = alien_width + 2 * alien_width * alien_number
	alien.rect.x = alien.x
	alien.rect.y = alien.rect.height + 2 * alien.rect.height * row_number
	aliens.add(alien)

def get_number_rows(ai_settings, ship_height, alien_height):
	"""计算屏幕可容纳多少行外星人"""
	available_space_y = (ai_settings.screen_heigh - (3 * alien_height) - ship_height)
	number_rows = int(available_space_y / (2 * alien_height))
	return number_rows

def update_aliens(ai_settings, screen, stats, sb, ship, aliens, bullets):
	"""检查是否有外星人位于屏幕边缘，并更新整群外星人的位置"""
	check_fleet_edges(ai_settings, aliens)
	aliens.update()

	# 检测外星人和飞船之间的碰撞
	if pygame.sprite.spritecollideany(ship, aliens):
		# print("ship hit!!!")
		ship_hit(ai_settings, screen, stats, sb, ship, aliens, bullets)

	# 检查外星人是否到达屏幕底端
	check_aliens_bottom(ai_settings, screen, stats, sb, ship, aliens, bullets)

def check_fleet_edges(ai_settings, aliens):
	"""有外星人到达边缘时采取相应的措施"""
	for alien in aliens.sprites():
		if alien.check_edges():
			change_fleet_direction(ai_settings, aliens)
			break

def change_fleet_direction(ai_settings, aliens):
	"""将整群外星人下移，并改变他们的方向"""
	for alien in aliens.sprites():
		alien.rect.y += ai_settings.fleet_drop_speed
	ai_settings.fleet_direction *= -1

def ship_hit(ai_settings, screen, stats, sb, ship, aliens, bullets):
	"""响应飞船被外星人撞到的飞船"""
	# 将ship_left减1
	if stats.ships_left > 0:
		stats.ships_left -= 1

		# 更新记分牌
		sb.prep_ships()

		# 清空外星人列表和子弹列表
		aliens.empty()
		bullets.empty()

		# 创建一群新的外星人，并将飞船放在屏幕底端中央
		create_fleet(ai_settings, screen, ship, aliens)
		ship.center_ship()

		#暂停
		sleep(0.5)
	else:
		stats.game_active = False
		pygame.mouse.set_visible(True)

def check_aliens_bottom(ai_settings, screen, stats, sb, ship, aliens, bullets):
	"""检查外星人是否到达屏幕底端"""
	screen_rect = screen.get_rect()
	for alien in aliens.sprites():
		if alien.rect.bottom >= (screen_rect.bottom):
			# 像飞船被撞到一样进行处理
			ship_hit(ai_settings, screen, stats, sb, ship, aliens, bullets)
			break

def check_high_score(stats, sb):
	"""检查是否诞生了新的最高得分"""
	if stats.score > stats.high_score:
		stats.high_score = stats.score
		sb.prep_high_score()